The present invention relates to a semiconductor radiological detector, and in particular, to a semiconductor radiological detector and a semiconductor radiological detecting apparatus which are suitably used in a two- or three-dimensional imaging apparatus.
A cross strip type radiological detector 100 shown in FIG. 10 is conventionally known as a semiconductor radiological detector (for example, Radiation Detection and Measurement, 3rd Edition (NIKKAN KOGYO SHINBUN LTD.), PP. 559–560). With a method of reading detection information (cross strip type reading method) which method is used in the cross strip type radiological detector 100 (hereinafter referred to as a semiconductor radiological detector 100), the position at which radioactive rays are incident is determined on the basis of as an X axis detected position and a Y axis detected position using a semiconductor device 101 composed of, for example, a cadmium telluride (CdTe) or the like to generate charges when irradiated with radioactive rays, a plurality of X axis strip electrodes (anodes) 102 extending so as to cross at right angles, and a plurality of Y axis strip electrodes (cathodes) 103. Then, two-dimensional incident position information is obtained by simultaneous measurements.
Accordingly, for example, for n×n pixels, the number of channels for individual reading is the same as the number of pixels (n×n). In contrast, with the cross strip type reading method, the number of reading channels is only 2×n, thus enabling the number of reading electrodes to be reduced (see, for example, Radiation Detection and Measurement, 3rd Edition (NIKKAN KOGYO SHINBUN LTD.), PP. 559–560). Specifically, if for example, the number of pixels on one side is 200, 200×200=40,000 reading channels are normally required. However, with the cross strip reading method, only 2×200 reading channels are required. That is, with the cross strip type reading method, the number of reading channels (the number of circuits) is 2×200/(200×200)=1/100. Therefore, the number of reading channels can be sharply reduced.
If the semiconductor radiological detectors 100, 100, described in Radiation Detection and Measurement, 3rd Edition (NIKKAN KOGYO SHINBUN LTD.), PP. 559–560, are arranged in parallel to increase the area of the detection surface, when a reading circuit is placed on a y ray incident side, the reading circuit may be an obstacle. Accordingly, a y ray incident side signal line must be drawn to a reading circuit located opposite the y ray incident side. To draw out signal lines 105 from the X axis strip electrode 102 to a Y axis wire 104, it is necessary to insulate the signal lines 105 so that the Y axis strip electrode 103 will not electrically contact with the signal lines 105. Thus, to draw out the signal lines 105 from the X axis strip electrode 102, the signal lines 105 must be bent like a circular arc, when connected to the Y axis wire 104, so as to run away from the Y axis strip electrode 102. As a result, as shown in FIG. 10, a dead space of size d for the signal lines 105 must be provided around the semiconductor radiological detector 100. This prevents a number of semiconductor radiological detectors 100 from being densely arranged. Thus, disadvantageously, the sensitivity, spatial resolution, and the like of the semiconductor radiological detector decrease, resulting in nonuniformity at joints.